This invention relates to a delay detonator which incorporates a transition element for providing a stable ignition signal to a delay train charge of the detonator.
A delay blasting cap or delay-action detonator, used for detonating high explosives, is an explosive charge which detonates at a certain time interval after the ignition signal is generated. Currently used delay detonators employ a variety of different ignition signal sources such as match heads, primer spots, percussion primers, and shock tubes. The ignition signals produced by these ignition sources are supplied to one end of the sequence or train of charges, known as a delay train or delay element, to ignite the delay train. The delay train, in turn, ignites a primary and/or base charge which is used to detonate high explosive charges.
The output or ignition signal produced by the typical ignition sources mentioned above is highly dependant upon the mass or weight of the reactable material of the source. Thus, variations in this mass or weight can result in an ignition signal whose burn rate and intensity varies according to the variation in the weight. The delay train burning rate is, in turn, highly dependant upon the burning intensity of the ignition signal at the time of ignition and so the time delay from ignition of the delay train to ignition of the base charge can similarly vary. Since it is difficult to fabricate ignition sources, of whatever kind, within tight tolerances, precision in the timing of initiation of explosive charges is difficult to achieve. Of course, close control of such timing is important if reliable, effective and safe blasting is to be accomplished.